U.S. Pat. Nos. 6,575,475; 6,595,242; 6,622,748; and 6,755,215 disclose a coupling used in testing water lines. This coupling includes a unitary, molded rubber or plastic cylindrical wall member with an internal removable disk between open ends of the cylindrical wall member. An annular ledge remains on the inside surface of the cylindrical wall member upon removal of the disk to form a pipe stop. A water pipe is placed in each open end of the cylindrical wall member to form a water line. An end of each water pipe is inserted into the open ends of the cylindrical wall member to abut opposite sides of the pipe stop. The thickness of this pipe stop is about 0.1 inch, and its maximum width is about 0.28 inch. The width is about equal to the wall thickness of the water pipes.
The water pipes may each be linear, non-branched pipes or one of the water pipes may be branched, for example a Tee-fitting or a Wye-fitting water pipe. A Tee-fitting water pipe has a straight section and branch section at a right angle to the straight section; a Wye-fitting water pipe has a straight section and branch section extending from its straight section at an acute angle. A pressure test is then conducted with water under pressure being fed into the upstream pipe, applying pressure to the upstream side of the disk. The elevated water pressure forces water through any upstream cracks or improperly sealed joints. Consequently, any leaks in any pipe joint or pipes upstream of the disk are thus located.
After testing, the disk is manually removed by tearing it away from the cylindrical wall member, thereby allowing water to flow through the coupled together upstream and downstream water pipes. This is accomplished typically by a pull member, for example, a strap having one end attached to the disk and another end extending from an opening in the downstream water pipe. This opening has a diameter sufficiently large to allow the disk torn from the cylindrical wall member to be pulled through the opening. After removal of the disk, water flows through the coupled together water pipes.
In U.S. Pat. No. 6,622,748 a cantilever device is used to puncture the disk to initiate a tear along a helical score line in the disk. One problem with this cantilever device is that, upon pressurizing the upstream water pipe, the disk bulges and a pointed tip of a piercing element of the cantilever device sometimes punctures the disk prematurely. Premature puncture of the disk prevents accomplishing the test because a leak in the disk is created through which water seeps. Another problem is that the helical score line often produces a jagged edge in the pipe stop that protrudes into the open cross-sectional flow area. After removal of the disk, the pipe stop should have an exposed edge that is smooth and circular and free of remnants that protrude into the open cross-sectional flow area. A jagged edge may reduce the “effective” open cross-sectional flow area of the pipe to create a flow obstruction to a degree that the water line fails to meet required plumbing specifications. Moreover, in some cases when using a downstream Wye-fitting water pipe, complete disk removal may not be achieved by simply pulling on the disk using the pull member.